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Effects of Polyoxymethylene Dimethyl Ether (PODE) Blended Fuel on Diesel Engine Emission
MUTIAN MA, Laura-Helena Rivellini, Nethmi Kasthuriarachchi, Qiren Zhu, Yichen Zong, Wenbin Yu, Wenming Yang, Markus Kraft, Alex Lee, National University of Singapore
Abstract Number: 313
Working Group: Combustion
Abstract
Diesel engine emission is one of the major sources of particulate matter (PM) that are associated with negative climate and health impacts. Studies have shown that Polyoxymethylene Dimethyl Ether (PODE) blended diesel can reduce total PM emission, yet few have studied its impact on PM chemical characteristics. This work investigates the effects of different PODE volume blends on diesel engine exhaust. Emissions were generated by a single-cylinder diesel engine test bed operated at low, medium, and high loading conditions (30%, 50%, and 60%, respectively). Black carbon (BC) and organic aerosol (OA) were characterized by a soot-particle aerosol mass spectrometer (SPAMS, Aerodyne Research) and a 7-wavelength aethalometer (AE33, Magee Scientific). The results show that OA was the dominant component contributing 45-75% of total PM mass. PODE reduced both BC and OA emissions in general with more prominent effect at low and high engine loadings (e.g. >70% reduction). While the OA-to-BC ratio decreased as the engine loading increased, this ratio increased with PODE vol%. In addition, positive matrix factorization (PMF) identified three hydrocarbon-like OA (HOA) components that were mixed with different mass fraction of BC. The mass fraction contribution of the factor with the lowest BC fraction increased as PODE vol% increased. This is likely due to PODE can reduce the fuel pyrolysis process and subsequently enhance the particle oxidation process which increased OA fraction. Brown carbon (BrC) absorption was observed across all PODE blends with the highest contribution to the total aerosol absorption under the low loading conditions (14%). Recent studies have found similar PMF factors (i.e., BC and HOA mixed in different degree) and BrC absorption contributions from on-road engine emissions. This work provides insights toward the changes in diesel engine emissions and its environmental implication caused by PODE blended fuel.